A computer simulation model has been developed for use in the study of demographic and genetic structure of small human populations. The model characterizes each individual in the population by age, sex, marital status, residence, reproductive history, surname or clan, and relationship to other members of the population, as well as by genotype (for real or hypothetical loci), and simulates the changing composition of the population as individuals marry, reproduce, migrate, or die. The computer program, which has already been used in several genetic and demographic studies, will be improved and documented, and made available to other geneticists, anthropologists, and demoraphers who are interested in small population analysis. In addition, this program, together with ancillary programs for genetic and demographic analysis, will be used for: (1) developing procedures to estimmte fertility, mortality, and migration rates in small populations; (2) assessing the relationsips between certain demographic and social factors and the genetic structure of small populations; and (3) evaluating the usefulness of certain genetic measuressin studies of human populations. In testing the model, we will rely heavily on an extensive body of data available for a French peasant population living in four partially isolated subdivisions, two on the island of St. Barthelemy, French West Indies and two on St. Thomas, U.S. Virgin Islands. However, our goal will be to develop techniques which are applicable to a wide variety of small human populations.